Flex circuits are used to electrically couple components together such that relative motion between the components is made possible while maintaining electrical coupling. Relative motion between components can be desirable in either the operation of the components or in their assembly. If the relative motion provided by the flex circuit is required for the operation of the components, the flex cycles can be as much as several thousand to hundreds of millions of flex cycles. If relative motion is provided by the flex circuit to facilitate assembly, the number of flex cycles can be as few as one or two flex cycles.
A hard disk drive (HDD) uses several flex circuits, known as flex cables in the HDD industry, which facilitate assembly as well as provide electrical coupling of components during HDD operation which require relative motion of the coupled components. The assembling of components in an HDD typically involve several operations wherein the flex cable is subjected to bending and at times overstressing due to the flex cable inappropriately interacting with a test fixture or an assembly tool. Examples of such inappropriate interaction of the flex cable with a test fixture or an assembly tool can be: pinching, chafing, scraping, creasing, tearing, and the like. The overstressing can go undetected until the flex cable fails a test at a higher level of assembly. Higher levels of assembly have higher cost associated with them since more components and more labor have been introduced to the flex cable at the higher level of assembly. An overstressed flex cable discovered at a higher level of assembly incurs more cost than if the overstressed flex cable had been discovered at a lower level of assembly.